Sergius II of Constantinople

Sergius II of Constantinople was the ninety ninth patriarch of Constantinople, serving from 999 to 1019. He was a firm opponent of the use of the term filioque in the creed.

Little is known of the early life of Sergius II. He was an abbot of a monastery in Constantinople when he was elected patriarch. The year he became patriarch is shown variously as either 999 or 1001. The date commonly used by the Orthodox is 999. He was among the first patriarchs to use the title Ecumenical Patriarch, this over the objections of the Pope of Rome.

Sergius II became patriarch during the time that the institution of charistikion was actively used within the empire. Charistikion was a practice wherein the donation (charistike dorea) of monasteries to private individuals was made supposedly to support the operation of monasteries, but in actuality was used by the wealthy gentry to gain income. This practice was strongly supported by emperor Basil for which his law Peri ton dynaton had been enacted. The institution of charistikion was not popular among the hierarchy and was challenged by Sergius' predecessor Patr. Sisinnios II. After he came to the see of Constantinople in 999, Patr. Sergius continued to resist the charistike dorea. However, as Emperor Basil refused to repeal his law, Patr. Sergius II resumed its use in 1016.

Sergius II was a firm opponent of the addition of the term filioque to the Nicene-Constantinopolitan Creed. Over this issue Sergius was alleged to have removed the name of the Pope of Rome, Sergius IV, from the diptychs of the Church of Constantinople, although often changes in the incumbency of the Roman throne meant that a Pope's name would be omitted on diptychs because of slow communications of the time.